Kohei Sakurai

Node status monitoring and state transition mechanism for network centric X-by-Wire systems

X-by-Wire systems are expected to enhance vehicle driving performance and safety. Regarding the dependable and cost-effective electronic platform for X-by-Wire systems, the network centric architecture is proposed based on a concept of autonomous decentralized systems. This architecture enables that, if one node fails, the remaining normal nodes autonomously execute a backup control to maintain the system function. This mechanism is served by a membership functionality implemented in a middleware that is independent from applications so that this mechanism can be applied to any applications. Following the concept proposal, the node status monitoring algorithm is designed because it is essential to identify the failed node accurately to execute the autonomous backup control. In this paper, to obtain a stability of a system throughout a driving, a sequence for autonomous start up and stop of the system is newly designed applying the node status monitoring function.

Cost-Effective and Fault Tolerant Vehicle Control Architecture for X-by-Wire Systems (Part 2: Implementation Design)

X-by-Wire systems are expected to enhance vehicle driving performance and safety. This paper describes an electronic platform architecture for X-by-Wire systems that satisfies both cost-effectiveness and dependability. In the first part of this paper (Part 1), we have proposed a new electronic architecture based on a concept of autonomous decentralized systems. In the latter part (Part 2), the proposed architecture implementation to the actual vehicle control systems will be discussed. We clarify that, due to system level redundancy the proposed architecture provides, vehicle control systems can basically consist of low cost fail-silent nodes. Furthermore, for cost optimization, considering a tradeoff between hardware cost and fault detection coverage, we design a suitable hardware architecture for each node according to node function.

Model Checking with Program Slicing Based on Variable Dependence Graphs

In embedded control systems, the potential risks of software defects have been increasing because of software complexity which leads to, for example, timing related problems. These defects are rarely found by tests or simulations. To detect such defects, we propose a modeling method which can generate software models for model checking with a program slicing technique based on a variable dependence graph. We have applied the proposed method to one case in automotive control software and demonstrated the effectiveness of the method. Furthermore, we developed a software tool to automate model generation and achieved a 35% decrease in total verification time on model checking.

Aiding Modular Design and Verification of Safety-Critical Time-Triggered Systems by Use of Executable Formal Specifications

Designing safety-critical systems is a complex process, and especially when the design is carried out at different levels of abstraction where the correctness of the design at one level is not automatically sustained over the next level. In this work we focus on time-triggered (TT) systems where the resources of communication and computation are shared among different applications to reduce the overall cost of the system. This entails serializing both communication and computation which does not necessarily meet the assumptions made by the application. Hence, we present the concept of executable formal specification of general TT systems to establish a faithful model of the TT characteristics. Our focus is on general applications running in a synchronous environment. The proposed model can be easily customized by the user and it is able to support simulation and verification of the system. It also aids the effective deployment of applications, and the validation of the real system with model-based test generation. Our case study shows how the general model can be implemented in the SAL language and how SALs tool suite can be used to guidethe design of general TT systems.

High Performance and Cost-Effective Electronic Controller Architecture for Powertrain Systems

Electronic controllers for powertrain systems are required to meet the demands for increased system performance and functionality at reasonable cost. It is indispensable to examine the solutions from a range of view points synthetically for cost optimization. This paper describes a cost-effective hardware and software architecture of the electronic controllers for powertrain systems. A new method for noise reduction of a switching regulator, and a low standby current wakeup solution are also discussed as further functions needed for high performance powertrain systems.